(1) Field of the Invention
The invention is related to a windshield mounting assembly with a windshield that is adapted to be arranged on an associated vehicle frame and at least one mounting frame that is attached to said windshield, said windshield mounting assembly comprising the features of claim 1.
(2) Description of Related Art
Vehicle frames can be provided with one or more windshields that are configured to embody aerodynamically formed windows on a given front of corresponding vehicles. These windshields are provided in order to protect occupants of the corresponding vehicles from wind and potentially flying debris, such as insects and dust.
In order to allow for an easy replacement of a windshield that is damaged or broken, the windshield can be mounted to an associated vehicle frame via a mounting frame. Such a mounting frame does not only allow for a quick and easy exchange of a damaged or broken windshield, but also enables a required compatibility between the associated vehicle frame and specific material properties of the windshield, as well as transfer of loads between the windshield and the associated vehicle frame in operation of an underlying vehicle.
However, depending on an underlying application of a given windshield, i.e. an associated vehicle frame, different maximum load requirements are applied to the windshield and thus, or in addition, specific geometric constraints must be considered when designing the windshield and an associated mounting frame. For instance, if the vehicle frame defines an airframe of a helicopter, the maximum applicable load requirements are very high if the helicopter has a maximum takeoff weight of more than 3.175 kg, as the windshield of such a helicopter must be able to sustain a bird strike. Furthermore, a minimum available area of visibility for a pilot of the helicopter must be provided and, thus, represents an important geometric constraint for the design of the windshield and the associated mounting frame.
The document US 2003/0062450 A1 describes a windshield mounting assembly comprising a windshield and a mounting frame which has an inner section with predetermined inner dimensions corresponding to outer dimensions of the windshield. The windshield is bonded to this inner section of the mounting frame, which further comprises an outer section with predetermined outer dimensions that are larger than the predetermined inner dimensions and correspond to dimensions of an attachment or frame structure of an airframe, to which the outer section of the mounting frame is screwed. Corresponding holes for receiving suitable screws are provided in the outer section of the mounting frame, which is larger than the windshield, such that the holes are arranged completely outside of the windshield area.
However, such a mounting frame reduces the available area of visibility of the pilot. Furthermore, such a mounting frame is often difficult to integrate because of underlying geometric constraints.
The document U.S. Pat. No. 2,784,926 describes a windshield mounting assembly comprising a windshield and an associated mounting frame that is adapted for attachment of the windshield to an associated airframe, where the windshield is provided with an outer edge that is clamped in the mounting frame. The outer edge is provided with spaced scallops or notches that are adapted to receive suitable screws or bolts that are passed through associated holes in a channeled seal strip which encompasses the outer edge of the windshield and which defines the mounting frame.
In this configuration, the windshield is secured in the mounting frame by being clamped therein. Thus, only a limited load transfer between the windshield and the airframe can be realized by the mounting frame. This limited load transfer is, however, not sufficient for sustaining large loads such as bird strike, especially on comparatively large helicopter windows.
The document US 2003/0010867 A1 describes an alternative possibility for attachment of a windshield to an airframe. Accordingly, the windshield is directly screwed to the airframe with screws passing through holes drilled through the material of the windshield. These holes are arranged in the area of an outer edge of the windshield.
However, some materials that are usually used to embody windshields have a comparatively low bearing strength and/or are sensitive to local stress concentration and notches (e.g. Polycarbonate). Thus, providing windshields that are made up of such materials with holes that are arranged in the area of an outer edge thereof would weaken the windshields and lead to an increased risk of damage or breakage of such windshields. Therefore, such windshields are not suitable for use with helicopters having comparatively high maximum load requirements, especially if bird-strike proof is required.
The document EP 2 107 001 A1 describes another alternative possibility for attachment of a windshield to an airframe, according to which the windshield is directly bonded to the airframe. However, in this case replacement of the windshield can be difficult and time-consuming if the windshield is damaged or broken in operation.
It should be noted that similar or different attachment possibilities and/or windshield mounting assemblies are described in the documents JP 11 245 660 A, KR 2002 0096698 A and JP 2005 306170 A. However, all of these attachment possibilities and/or windshield mounting assemblies have at least one of the above described drawbacks.